1. Field of the Invention
The present invention relates to spring operated fire safety devices that are thermally activated to extend a pin and connect two objects, such as a fire door and an adjacent floor or doorframe.
2. Description of Related Art
Fire doors are designed to limit the spread of a fire within a building by preventing the passage of heat, smoke, flames and oxygen required for combustion. Fire safety regulations require that fire doors and door hardware resist the high temperature of a fire that they may be exposed to and hold the door securely closed.
Fire resistant steel doors are often used in these applications and will prevent the passage of fire through the door itself. However, steel doors may warp and move away from the doorframe or an adjacent door if subjected to very high temperatures. Any opening between a warped fire door and the doorframe may allow the escape of fire and smoke from the fire area and allow oxygen to pass into the fire area. Warping under extreme heat is a particularly difficult problem to solve when the door opening is two doors wide and two adjacent doors latch at the center of the opening.
This type of double door opening is found in many public buildings. Although the wide door opening allows for rapid movement of many people through the opening, the two adjacent doors may change shape and warp in different directions under intense heat. This differential warping increases the chance that an unacceptably wide opening will be created between the doors and allows the fire to pass through.
Warping is most easily controlled by door hardware incorporating vertical rods that latch at the top and bottom of the door to connect the door to the door frame and the floor. However, there are many door installations where it is desirable to eliminate the lower vertical rod to avoid the possibility of damage to the flooring. In these single vertical rod door hardware installations, there is a need to latch the bottom of the door to the floor or to another fixed object during a fire to prevent warping.
There are many other fire safety applications for thermally activated pin assemblies to ensure that two objects do not move relative to each other during a fire due to warping of components capable of resisting high temperatures or due to melting of lower temperature components door hardware.